The transfer of information between electronic devices is now an important activity in everyday life. Often electronic information transfers occur via wired communication links involving networks that require substantial set-up and/or installation costs. Problems occur when information needs to be transferred between mobile devices because wired connections are cumbersome and tend to negate the usefulness and mobility of the devices.
There are methods and devices that facilitate wireless information transfer, but most conventional wireless networks do little more than replace wire lines with wireless communication links. A significant amount of infrastructure and user involvement in setup procedures is still common.
Certain mobile communication devices reduce the infrastructure problem by facilitating information transfer with widely accepted protocols and avoiding the need for wired networks. These devices, such as PDAs, digital cameras, cell phones, and other mobile devices, are effective in situations where information needs to be transferred between mobile devices not normally connected to networks. However, one problem with these larger devices is that they are generally too large to be carried around by a person and stored compactly in a wallet, slipped into a small purse, tucked in a pocket, or carried in some other manner on a person. This is due in part to the relatively large batteries that are needed to power cell phones, PDAs, and similar mobile devices.
As society becomes more information dependent, individuals carry an increasing amount of information on their person. In the past, the information has been encoded onto physical devices or cards that are then tucked inside a wallet or a purse or simply carried in a pocket. A multitude of cards or devices are inconvenient because in order for the information encoded devices and cards to be useful, the individual must physically carry them around anticipating their use. Eventually, the wallet, pocket, or purse gets bulky when carrying everything one might anticipate using. When the cards and devices are used they must be physically removed, as from the wallet, and then returned upon completion of the transaction.
By digitizing the information contained on the encoded devices and selectively transferring the information over a wireless link via a PDA-sized mobile communication device, these problems are partially solved. But a new problem is created because the information is merely transferred from the bulky devices or cards to a bulky PDA-sized device that facilitates the information transfer. PDAs and similar devices are sometimes too big to be conveniently carried, imposing an additional burden on the individual.
Smart card technology accommodates the size restrictions of storing information on a device which is easily carried. A smart card is generally a credit-card sized device with an embedded computer chip. The chip can either be a microprocessor with internal memory or a memory chip with non-programmable logic. A smart card generally has no user interface and the card is generally powered from an external source. Typically, a smart card is inserted into another device that allows a user to enter and retrieve information from the card. Thus, a smart card is usually physically docked with another read/write device to transfer information. Some smart cards can facilitate information transfer without direct physical contact with another device. These cards rely on a contactless electromagnetic interface to transfer information. The disadvantage of this system is limited range—usually 25 centimeters or less. Often it is not feasible or convenient to transfer information from a device within a range of just a few centimeters, especially if the device is located within a wallet or a purse.
Certain mobile communication devices assist in transferring information from smart cards at distances greater than a few centimeters. These devices allow the information on the card to be securely transferred in environments with a large number of communication devices. For example, information can be wirelessly transferred in a Point-of-Sale transaction, or other similar transactions where the information is personal and/or restricted in some way. The devices may include the smart card interface, a keypad, a display, a radio, an antenna, and a battery. A smart card is connected to these communication devices (e.g., a PDA), which facilitate the transfer of the information contained on the card. However, these devices are also bulky and do not fit inside a wallet. Like the devices above, these devices are also cumbersome and difficult to carry.
Some mobile devices make use of an embedded Bluetooth radio to facilitate the transfer of information. Bluetooth is a technology based on a short-range radio link that facilitates protected, ad-hoc connections for stationary and mobile communication units in Wireless Personal Area Network (WPAN) environments. Bluetooth technology allows for communication links connecting mobile communication devices over a range of 10 centimeters to 100 meters. Further, Bluetooth technology is designed to operate in a noisy radio frequency environment, and uses a frequency-hopping scheme to make the communication link robust.
One disadvantage of certain wireless communication technologies (such as Bluetooth) is the amount of time required to discover and fully connect with other mobile communication devices. Setting up a connection using Bluetooth takes ten seconds or even longer when the ideal conditions are not present. Long connect times (e.g., ten seconds) may be unacceptable in emergency communication situations, with multiple device interactions, or in circumstances in which two mobile devices may quickly pass out of range. Suppose communication is intended between two mobile devices approaching one another from opposite directions. Although communication may be intended, the devices may cross paths and be out of range before the device discovery process is complete.
Another significant problem with mobile wireless communication devices is power consumption. Mobility in portable devices is directly linked to the life of the battery power supply. Because of size and weight restrictions associated with mobile devices, limiting power consumption is a high priority. Reducing power consumption is important in devices that utilize wireless communication technologies, such as Bluetooth. As an example, in Bluetooth active mode, data transmission consumes a large amount of power. Even in idle or standby mode, Bluetooth modules and comparable modules consume power responding to discovery inquiries from other wireless devices that enter the WPAN space.